Bragg grating sensor system with spectral response or code division multiplexing

Abstract

The present invention provides a sensor system for sensing a parameter, comprising an optical source, coupler and signal processor system in combination with multiple structured fiber Bragg gratings. The optical source, coupler and signal processor system provide an optical source signal to the multiple structured fiber Bragg gratings. The optical source, coupler and signal processor system also responds to multiple structured fiber Bragg grating signals, for providing an optical source, coupler and signal processor system signal containing information about a sensed parameter. The multiple structured fiber Bragg gratings respond to the optical source signal, and further respond to the sensed parameter, for providing the multiple structured fiber Bragg grating signals containing information about a complex superposition of spectral responses or codes related to the sensed parameter. Each of the multiple structured fiber Bragg gratings includes a respective broadband spectral response or code related to the sensed parameter.

Description

BACKGROUND OF INVENTION1. Technical FieldThe present invention relates to a Bragg grating sensor system in which resonance characteristics of a grating reflector are tailored to provide each sensor element in a series of elements with a unique spectral identity, or signature. Unlike normal grating sensors, where the gratings need to be separated in wavelength, this feature allows several gratings to occupy the same wavelength space. The overlapping spectral features of each grating are detected via the use of a spectral, matched filter correlation technique.2. Description of Related ArtFIG. 1 shows a sensor system that is known in the art and includes fiber Bragg grating based sensors that provide a wavelength encoded mode of operation. To multiplex several sensors along a fiber, each grating is typically assigned a certain wavelength range over which it is to operate. This method of wavelength division multiplexing (WDM) limits the number of sensors which can be multiplexed, partic...

AI Technical Summary

Benefits of technology

The foregoing and other objects, features and advantages of the present invention will become more apparent in light of the following detailed description of exemplary embodiments thereof, as illustrated in the accompanying drawing.

Problems solved by technology

This method of wavelength division multiplexing (WDM) limits the number of sensors which can be multiplexed, particularly if the gratings are subjected to large strains or temperature changes which give rise to large wavelength shifts.

Unfortunately, when multiplexing grating sensors, the limited wavelength range that can be assigned to each sensor limits the responsivity that can be used.

Images